Compaq Computer Corporation, Inc.

Gill Watt

James Arthur Farrell

Nevine Nassif

Harry Ray Fair, Iii

Dale Hayward Hall

A system for accurately determining Elmore delays in DCVSL structures is disclosed. The system uses circuit simulation to determine models for Elmore delays through devices within specific circuit structures. The circuit structures include DCVSL circuits to accurately model performance of devices with such a structure. The system also determines discharge characteristics for DCVSL circuits using simulation. In order to determine Elmore delays, the system analyzes a circuit representation to locate DCVSL structures. The discharge characteristics and models are used to determine Elmore delays for each structure located.

Method and apparatus for performing timing verification of a circuit

A method and apparatus for determining load capacitance of DCVSL circuits in timing verification of a circuit is disclosed in the present invention. The gate capacitances for various MOS devices are modeled based upon simulations with certain conditions for inputs to the gate, source and drain. The system then determines the existence of DCVSL circuits within the topology of a circuit, and applies one of several models to determine minimum and maximum capacitances for the encountered DCVSL structures. The determination of minimum and maximum capacitance depends upon the selected model and the capacitance of each of the MOS devices as previously calculated.

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Acton, MA, United States of America

Gill Watt